1) Field of the Invention
The present invention relates to a closure, particularly for use on containers for packing liquid products, especially carbonated beverages, as well as to a container for packing products, especially carbonated beverages, which comprises the closure aimed at herein.
2) Description of Related Art
Conventionally the packing of carbonated beverages, such as soft drinks in general, is problematic due to the high pressure inside the packing containers, such as bottles or cans.
Considering that nowadays, specifically in the case of bottles, there is a predominance of those that enable one to consume only a part of the product, the old metallic caps that were removed with a bottle-opener and did not allow one to close the bottle afterwards tend to disappear, notably in the field of soft drinks.
By virtue of the characteristics of packed carbonated beverages, there has always been the objective of conceiving a closure that could enable one to maintain the levels of gas in the beverage, even after successive openings, so as to ensure the flavor of the product as long as possible.
Therefore, the closure of a carbonated-beverage bottle should meet a number of functioning requirements that are extremely difficult to reach, mainly because their manufacturing costs should be kept as low as possible, that is to say:
1) first of all, the closure should bear a high pressure existing inside the battle, without presenting gas leakage and consequent decrease in pressure before the opening. This internal pressure may reach very high values, if the bottle is placed in the sunshine or in other places where the temperature is high, and/or in the event of the bottle being successively shaken, a situation in which a portion of gas, which was dissolved in the beverage, now occupies the empty space inside the bottle.
2) Secondly, the closure should have one or more sealing elements, which enables it to continue to prevent leakages of gas, even after successive openings of the bottle, in order to bring about a partial consumption of the beverage packed therein without a considerable loss of flavor.
3) Thirdly, evidently the closure should prevent leakage of liquids under any condition of use that is not an exception to the situations foreseen in design.
In an almost universal way, carbonated-beverage bottles have a threaded neck, to which a screwable closure is associated, which may be opened and closed many times. However, in order to guarantee the inviolability of the beverage between the place of manufacture and the moment at which the consumer opens the bottle, virtually all the closures have a anti-tamper seal, the functioning principle of which is based on the weakness of a determined region of the closure, so that, when the latter is unscrewed for the fist time, the weak region present an at least partial or visible break, which clearly indicates that the bottle has been opened.
Until now, the best closures for this kind of use are the so-called 2-piece closures, which, in addition to the carcass material, also have another constituent called “sealing”, the plastic matter of which is usually elastomeric and flexible in order to provide a more accurate effect of accommodation on the bottle neck, bringing about a safer and more effective sealing. The practice of the industry is to use the 2-piece closures in applications where one requires the best tightness possible, which is exactly the case of the packing of carbonated beverages. Although there are carbonated-beverage bottles using single-piece closures, in general the closures that have a sealing are the best choice, since it provides the best retention of gas inside the beverage. However, the single-piece closures are, in general, more economical, less expensive, and one should always try to find the optimum point between the cost and the benefit.
Within this scenery, a number of inventions have been made lately with a view to obtain a single-piece closure capable of being successfully applied to carbonated-beverage bottles. Some of these inventions show the error of incrementing too much the mass of plastic matter (weight) of the closure in order to have a robust and efficient sealing system, which, however, entails extra costs that end up by making the project more expensive than that of a two-piece closure. In a general way, the objective is to develop a single-piece closure having an optimum point between its cost and its performance in retaining gas, which is a great advantage for the sector of carbonated-beverage industry.
It should be reminded that the single-piece closures are those that have a single constituent, that is to say, the matter that composes it is single and is the one that forms its carcass as a whole.
With a view to achieving the above objectives, a single-piece closure was developed and disclosed in U.S. Pat. No. 5,259,522 for use on packages, which comprises a substantially circular upper wall from which a cylindrical side wall provided with inner threads extends.
This closure also has two sealing elements comprising a relatively rigid annular support and a flexible sealing lip, which are positioned internally on said cylindrical side wall.
When the closure is screwed onto the bottle-neck, the sealing lip deforms in contact with the outer surface of the latter, while the relatively rigid annular support maximizes or potentializes the sealing effect of the sealing lip. Additionally, the relative rigidity of the annular support brings about the centering of closure with respect to the bottle-neck during its application, at the moment of packing the beverage. Evidently, this centering occurs whenever the closure is screwed onto the bottle-neck again, after successive openings.
The closure disclosed in this patent further comprises an anti-taper seal that functions in the manner described above.
However, due to the fact that the closure has only this side sealing achieved by the above-mentioned elements, the effective protection against leakage of gas still had not been achieved, notably when the filled bottle was subjected to unfavorable situations, such as high temperatures and excessive manipulation.
Another single-piece closure, now made by the applicant itself, is disclosed in patent document MU 7600036-2 and comprises a first circular surface, from the end of which a cylindrical wall extends. This closure has at least one first axial sealing element cooperating with the inner surface of the bottle-neck, at least one second axial sealing element cooperating with the upper surface defined by the wall of the bottle-neck and, finally, at least one third radial sealing element, provided on the inner surface of the side wall and cooperating with the outer surface of the bottle-neck. This closure also has an anti-tamper seal.
Although the closure disclosed in this document functions well under normal conditions, an excessive increase in pressure inside the bottle causes the upper circular surface to deform, a bulging or “belly” resulting. When this surface is deformed, the possibility of occurring leakages increases.